Subatomic particles

Photo by: Patrick Hermans

Subatomic particles are particles that are smaller than an atom. In 1940,
the number of subatomic particles known to science could be counted on the
fingers of one hand: protons, neutrons, electrons, neutrinos, and
positrons. The first three particles were known to be the building blocks
from which atoms are made: protons and neutrons in atomic nuclei and
electrons in orbit around those nuclei. Neutrinos and positrons were
somewhat peculiar particles discovered outside Earth's atmosphere
and of uncertain origin or significance.

That view of matter changed dramatically over the next two decades. With
the invention of particle accelerators (atom-smashers) and the discovery
of nuclear fission and fusion, the number of known subatomic particles
increased. Scientists discovered a number of particles that exist at
energies higher than those normally observed in our everyday lives: sigma
particles, lambda particles, delta particles, epsilon particles, and other
particles in positive, negative, and neutral forms. By the end of the
1950s, so many subatomic particles had been discovered that some
physicists referred to their list as a "particle zoo."

The quark model

In 1964, American physicist Murray Gell-Mann (1929– ) and Swiss
physicist George Zweig (1937– ) independently suggested a way out
of the particle zoo. They suggested that the nearly 100 subatomic
particles that had been discovered so far were not really elementary
(fundamental) particles. Instead, they suggested that only a relatively
few elementary particles existed, and the other subatomic particles that
had been
discovered were composed of various combinations of these truly
elementary particles.

Words to Know

Antiparticles:
Subatomic particles similar to the proton, neutron, electron, and other
subatomic particles, but having one property (such as electric charge)
opposite them.

Atomic mass unit (amu):
A unit of mass measurement for small particles.

Atomic number:
The number of protons in the nucleus of an atom.

Elementary particle:
A subatomic particle that cannot be broken down into any simpler
particle.

Energy levels:
The regions in an atom in which electrons are most likely to be found.

Gluon:
The elementary particle thought to be responsible for carrying the
strong force (which binds together neutrons and protons in the atomic
nucleus).

Graviton:
The elementary particle thought to be responsible for carrying the
gravitational force.

Isotopes:
Forms of an element in which atoms have the same number of protons but
different numbers of neutrons.

Lepton:
A type of elementary particle.

Photon:
An elementary particle that carries electromagnetic force.

Quark:
A type of elementary particle.

Spin:
A fundamental property of all subatomic particles corresponding to
their rotation on their axes.

The truly elementary particles were given the names quarks and leptons.
Each group of particles, in turn, consists of six different types of
particles. The six quarks, for example, were given the rather fanciful
names of up, down, charm, strange, top (or truth), and bottom (or beauty).
These six quarks could be combined, according to Gell-Mann and Zweig, to
produce particles such as the proton (two up quarks and one down quark)
and the neutron (one up quark and two down quarks).

In addition to quarks and leptons, scientists hypothesized the existence
of certain particles that "carry" various kinds of forces.
One of those particles was already well known, the photon. The photon is a
strange type of particle with no mass that apparently is responsible for
the transmission of electromagnetic energy from one place to another.

In the 1980s, three other force-carrying particles were also discovered:
the W
+
, W
−
, and Z
0
bosons. These particles carry certain forces that can be observed during
the radioactive decay of matter. (Radioactive elements spontaneously emit
energy in the form of particles or waves by disintegration of their atomic
nuclei.) Scientists have hypothesized the existence of two other
force-carrying particles, one that carries the strong force, the gluon
(which binds together protons and neutrons in the nucleus), and one that
carries gravitational force, the graviton.

Five important subatomic particles

For most beginning science students, the five most important sub-atomic
particles are the proton, neutron, electron, neutrino, and positron. Each
of these particles can be described completely by its mass, electric
charge, and spin. Because the mass of subatomic particles is so small, it
is usually not measured in ounces or grams but in atomic mass units
(label: amu) or electron volts (label: eV). An atomic mass unit is
approximately equal to the mass of a proton or neutron. An electron volt
is actually a unit of energy but can be used to measure mass because of
the relationship between mass and energy (E = mc
2
).

All subatomic particles (indeed, all particles) can have one of three
electric charges: positive, negative, or none (neutral). All subatomic
particles also have a property known as spin, meaning that they rotate on
their axes in much the same way that planets such as Earth do. In general,
the spin of a subatomic particle can be clockwise or counterclockwise,
although the details of particle spin can become quite complex.

Proton.
The proton is a positively charged subatomic particle with an atomic mass
of about 1 amu. Protons are one of the fundamental constituents of all
atoms. Along with neutrons, they are found in a very concentrated region
of space within atoms referred to as the nucleus.

The number of protons determines the chemical identity of an atom. This
property is so important that it is given a special name: the atomic
number. Each element in the periodic table has a unique number of protons
in its nucleus and, hence, a unique atomic number.

Neutron.
A neutron has a mass of about 1 amu and no electric charge. It is found
in the nuclei of atoms along with protons. The neutron is normally
a stable particle in that it can remain unchanged within the nucleus for
an infinite period of time. Under some circumstances, however, a neutron
can undergo spontaneous decay, breaking apart into a proton and an
electron. When not contained with an atomic nucleus, the half-life for
this change—the time required for half of any sample of neutrons to
undergo decay—is about 11 minutes.

The nuclei of all atoms with the exception of the hydrogen-1 isotope
contain neutrons. The nuclei of atoms of any one element may contain
different numbers of neutrons. For example, the element carbon is made of
at least three different kinds of atoms. The nuclei of all three kinds of
atoms contain six protons. But some nuclei contain six neutrons, others
contain seven neutrons, and still others contain eight neutrons. These
forms of an element that contain the same number of protons but different
numbers of neutrons are known as isotopes of the element.

Electron.
Electrons are particles carrying a single unit of negative electricity
with a mass of about 1/1800 amu, or 0.0055 amu. All atoms contain one or
more electrons located in the space outside the atomic nucleus. Electrons
are arranged in specific regions of the atom known as energy levels. Each
energy level in an atom may contain some maximum number of electrons,
ranging from a minimum of two to a maximum of eight.

Electrons are leptons. Unlike protons and neutrons, they are not thought
to consist of any smaller particles but are regarded themselves as
elementary particles that cannot be broken down into anything simpler.

All electrical phenomena are caused by the existence or absence of
electrons or by their movement through a material.

Neutrino.
Neutrinos are elusive subatomic particles that are created by some of the
most basic physical processes of the universe, like decay of radioactive
elements and fusion reactions that power the Sun. They were originally
hypothesized in 1930 by Swiss physicist Wolfgang Pauli (1900–1958).
Pauli was trying to find a way to explain the apparent loss of energy that
occurs during certain nuclear reactions.

Neutrinos ("little neutrons") proved very difficult to
actually find in nature, however. They have no electrical charge and
possibly no mass. They rarely interact with other matter. They can
penetrate nearly any form of matter by sliding through the spaces between
atoms. Because of these properties, neutrinos escaped detection for 25
years after Pauli's prediction.

Then, in 1956, American physicists Frederick Reines and Clyde Cowan
succeeded in detecting neutrinos produced by the nuclear reactors at the
Savannah River Reactor. By 1962, the particle accelerator at
Brookhaven National Laboratory was generating enough neutrinos to conduct
an experiment on their properties. Later, physicists discovered a second
type of neutrino, the muon neutrino.

Traditionally, scientists have thought that neutrinos have zero mass
because no experiment has ever detected mass. If neutrinos do have a mass,
it must be less than about one hundred-millionth the mass of the proton,
the sensitivity limit of the experiments. Experiments conducted during
late 1994 at Los Alamos National Laboratory hinted at the possibility that
neutrinos do have a very small, but nonzero, mass. Then in 1998, Japanese
researchers found evidence that neutrinos have at least a small mass, but
their experiments did not allow them to determine the exact value for the
mass.

In 2000, at the Fermi National Accelerator Laboratory near Chicago, a team
of 54 physicists from the United States, Japan, South Korea, and

Electronic display of energies from subatomic particles.
(Reproduced by permission of

Photo Researchers, Inc.

)

Greece detected a third type of neutrino, the tau neutrino, considered to
be the most elusive member of the neutrino family.

Positron.
A positron is a subatomic particle identical in every way to an electron
except for its electric charge. It carries a single unit of positive
electricity rather than a single unit of negative electricity.

The positron was hypothesized in the late 1900s by English physicist Paul
Dirac (1902–1984) and was first observed by American physicist Carl
Anderson (1905–1991) in a cosmic ray shower. The positron was the
first antiparticle discovered—the first particle that has
properties similar to protons, neutrons, and electrons, but with one
property exactly the opposite of them.

there really is no relation between mass and the particles charge its charge is relative to the particles spin not its mass for example a photon is massless yet it has a plus one charge. and in this it call the particle responsible for gravity a graviton and its actual name is the higgs particle

The term antimatter can give you the idea of something un existing.But if you ask ("what is its use?")bring you to the reality of its existence.
For instance: I ask Google " Wat is the use of Positron?", & ther came to me Positron Emission Tomography (PET) of multiple uses.
So in physics, or at any other question, a phylosofical enquire should allways be: Does it work? Then it exist.Thanks for Lesson.

Impossible to get a straight answer anywhere: How many subatomic particles are there? Obvioulsy the answer is "It depends!" What technology has been derived exclusively from high energy particle physics? The answer is NONE. It's one giant, expensive fantasy land.

Scientists are good at breaking up things; for example they collide sub atomic particles into still more sub sub atomic particles.

What about they find out how to put the sub sub particles together and stay together, as it was in its original status prior to being collided on by other particles and gotten disintegrated into still more sub sub particles?